Bronchopulmonary dysplasia: pathophysiology and clinical management

Bronchopulmonary Dysplasia or (BPD) is a chronic lung disease of babies, which develops most commonly in the first four weeks after birth. It mostly occurs in babies who are born more than 4 weeks before their due dates, though sometimes the babies are full term. In BPD, the lungs do not work properly and the babies have trouble breathing. They need extra oxygen and may even need help from a breathing machine. Doctors think babies get BPD because their lungs are sensitive to something damaging in the environment, such as oxygen, a breathing machine, or an infection. Premature babies are also at risk for complications in other parts of the body that are also not fully mature, including the heart, kidneys, brain, stomach, intestines, and eyes. With new and better treatments today, most babies with BPD live. In severe cases, the baby may die (www.nhlbi.nih.gov.health/dci/Diseases/BPD/Bpd_WhatIs.html.).

BPD is different from Respiratory Distress Syndrome or RDS, which occurs in the lungs of premature infants, because their lungs do not produce enough surfactant or a liquid material that coats the inside of the lungs making it easy to breathe. In the past, doctors thought that BPD was a disease mostly in babies who survived RDS. They believed that the treatment of RDS with a breathing machine and extra oxygen caused BPD. Today, babies with RDS are treated with surfactant replacement therapy. With this new treatment, BPD is not common in babies born early and weighing 3 pounds or more. This rules out RDS as the main cause of BPD. Still treatment of antenatal glucocorticosteroids, early surfactant therapy, and gentler modalities of ventilation have minimized the severity of lung injury, particularly in more mature infants. However, in some smaller infants who may have been exposed to chronic chorioamnionitis, its pathogenesis remains mysterious.

The pathophysiology of BPD is includes multiple organ involvement. Major organ systems affected include the lungs and the heart. Specifically the alveoli of the lung are more susceptible because the alveolar stage of lung development in the human is from about 36 weeks' gestation to 18 months postnatally, with most alveolarization occurring within 5 to 6 months of term birth. Although primary septation forms saccules and secondary septal crests indicate alveolarization, some doctors think that septations are a continuous process. The intense pulmonary microvasculature branching runs parallel with lung development; however, detailed understanding of their interactions and interactions with various growth factors is elusive (www.emedicine.com).

What causes BPD is unique to each neonatal situation. However, high levels of extra oxygen can harm the lungs, cause inflammation, and slow or stop the lung growth in babies born very early. Babies who need a high level of extra oxygen for a period of time may develop BPD. Babies who cannot breathe on their own have breathing failure. Many of these babies are put on a breathing machine to help them breathe. The pressure that the machine uses to push the air can irritate the airways and the lungs and cause them to become more inflamed. Also babies can be exposed to infections both in the womb and after birth. Infections in babies born early can harm their less formed lungs and cause them to become inflamed. Lung infections also increase the baby's need for extra oxygen (www.nhlbi.nih.gov.health/dci/Diseases/BPD/Bpd_WhatIs.html.).